With the wide spread use of digital signal processing in a variety of electrical apparatuses in recent years, it has now become a mainstream for those apparatuses to employ digital signals for input and output of signals.
Rotary encoders are used in many cases for those apparatuses as electronic devices that output digital signals of rectangular waveforms.
Japanese Unexamined Patent Publication, No. H07-141960 shows one example of the conventional rotary encoders. In the above conventional rotary encoder, electrode 910 is disposed to cover entirely the circumference thereof, as shown in FIG. 13. Therefore, a sheet metal of good electrical conductivity, or a material to form electrode 910 needs to have at least width “W” of the electrode portion shown in FIG. 13. It was hence difficult to reduce a width dimension of the material.
Furthermore, due to advancement toward multi-functional capability of the apparatuses, rotary encoders used therein are operated more frequently than before. This trend has given rise to a problem of durability on many such rotary encoders since common contact point 953, first contact point 951 and second contact point 952 are all subjected to sliding abrasion of increased frequency and distance.